1. Field of the Invention
One embodiment of the present invention relates to an electronic circuit and a method for driving the electronic circuit. Moreover, one embodiment of the present invention relates to a display device. Further, one embodiment of the present invention relates to an electronic device including the display device in a display portion.
2. Description of the Related Art
In recent years, with the increase of large display devices such as liquid crystal televisions, display devices such as liquid crystal display devices and light-emitting devices have been actively developed. In particular, a technique for forming a pixel circuit and a driver circuit in a display device over the same insulating substrate by using thin film transistors or the like including semiconductor layers provided over the insulating substrate has been actively developed, because the technique greatly contributes to reduction in power consumption and cost, for example. The driver circuit formed over the insulating substrate is connected to a circuit including a controller IC through an FPC, for example, and its operation is controlled by the controller IC.
Examples of the driver circuit in the display device are a scan line driver circuit and a signal line driver circuit. For example, as disclosed in Patent Document 1, a driver circuit is constituted by a shift register, which is a kind of electronic circuit. The shift register is constituted by sequential circuits of plural stages including a plurality of sequential circuits such as flip-flops.
In order to operate the shift register more correctly, it is preferable to control the state of an output signal from a flip-flop in each operation period so as to be a desired state, for example. If the state of the output signal from the flip-flop cannot be controlled to be a desired state due to adverse effects of noise, for example, it is highly likely that the shift register malfunctions.